Effect of Explant Types and Growth Regulators on Callus induction and Secondary Metabolites of Chicory (Cichorium intybus L.)

Chicory (Cichorium intybus L.) is an important medicinal plant with valuable medicinal metabolites. Chicory callus can be a good source for the production and extraction of secondary metabolites of this plant. Concentration of growth regulators and type of explants are the main factors affecting the production of chicory callus. The aim of this study was optimization of the callus and secondary metabolites production in chicory using the different concentration of growth regulators and explant types.

The effect of different concentration of Benzyladenine (BA) (0, 0.5, 1, 2 mg/L and Naphthale acetic acid (NAA) (0, 0.5, 1 mg/L) and explants (petiole, stem and Leaf) on callus formation, phenolic and flavonoid production in chicory was investigated in a factorial based on completely randomized design experiment with three replications. First, the seeds were surface sterilized and then, they were cultured in MS medium to produce sterile seedlings. After 4 to 5 weeks, Leaf, petiole and stem explants were prepared from seedlings in sterile conditions. The explants were cultured in tissue culture medium containing different concentrations of BA and NAA. After 4 weeks, calluses obtained from sterile explants were used to measure the percentage of callus production, fresh and dry weight, dry matter percentage, callus relative water content, phenolic, flavonoid and antioxidant activity.

Based on the results of variance analysis, the interaction of all treatments showed a significant difference at 1% level as compared to the control. The comparison of interactions between treatments showed that petiole explants had the highest callus production in the medium suplemented with 2 mg/L BA with 1 mg/L NAA. On the other hand, the highest callus fresh weight was obtained in leaf explant in treatment of 0.5 mg/L BA with 0.5 mg/L NAA. In addition, the highest callus dry weight was obtained in petiole and stem explant in treatment of 1 and 2 mg/L BA with 0.5 mg/L NAA. The highest percentage of callus dry matter observed in petiole explant in the medium suplemented with 1 mg/L BA and 0.5 mg/L NAA. The highest phenol and flavonoid content observed in petiole explant in the medium suplemented with of 0.5 mg/L BA alone. The callus produced from the stem explants showed the highest antioxidant activity in the treatment of 1 mg/L BA and 1 mg/L NAA.

Overall, the best explant for callus production was petiole in combination with treatments of 2 mg/L BA and 1 mg/L NAA or the medium containing 0.5 mg/L BA without NAA. Moreover, the above treatments produced the highest levels of phenol and flavonoids, which had the most antioxidant activity too.